Boosting Photodetection via Plasmonic Coupling in Quasi‐2D Mixed‐n Ruddlesden‐Popper Perovskite Nanostripes

Abstract Quasi‐2D metal halide perovskites have emerged as a promising material for photodetection due to excellent optoelectronic properties, simple synthesis, and robust stability. Albeit, developing high‐performance photodetectors based on low‐dimensional quasi‐2D metal halide perovskite nanoparticles remains challenging due to quantum and dielectric confinement effects. Several approaches are employed to improve efficiency, with plasmonic nanostructures being among the most effective ones. Here, enhanced photodetection of quasi‐2D perovskite nanostripes are demonstrated resulting from the incorporation of octadecanethiol (ODT)‐functionalized Ag nanostructure arrays (ANA). Using colloidal lithography, ANA are fabricated. Reflectance spectroscopy and finite element method (FEM) simulations show that ANA supports localized surface plasmon resonance (LSPR) modes that spectrally coincide with the absorption and emission band of the perovskite. This spectral overlap enables interesting coupling interactions between the excitons and plasmons. The ODT‐functionalized ANA photodetectors exhibit weak to intermediate coupling facilitating resonant energy transfer, resulting in a photocurrent enhancement factor of 838 %. They achieve photoresponsivities of up to 70.41 mA W ⁻¹ , detectivities of 1.48 × 1011 Jones and external quantum efficiencies of 21.55%, which are approximately ten times higher than those of the reference photodetector. This study proposes a strategy to optimize plasmon‐exciton coupling and resonant energy transfer for high‐performance plasmonic‐perovskite photodetectors.